The goals of this research study are to identify psychophysiologic and behavioral correlates of pituitary-adrenal disinhibition in endogenous depression, to examine the specificity to endogenous depression of any association between the psychophysiologic and behavioral variables and the neuroendocrine abnormality and to define further the regulation of the pituitary peptides, corticotropin and vasopressin, in psychiatric patients showing a failure to suppress cortisol after dexamethasone. Interrelationships between disorders of mood and those of pituitary-adrenal dysfunction represent some of the most consistently reproducible findings in biological psychiatry. The failure of approximately 50% of depressed patients to suppress cortisol or show an escape from suppression after dexamethasone treatment has recently gained prominence as a factor that may be useful in psychiatric diagnosis, selection of appropriate treatment and monitoring of treatment response. More recently, there appears to be evidence that individuals who do not appear clinically depressed but who do show a failure to suppress may have similar treatment response and course of illness as those patients with more classical signs of depression who also show non-suppression. Thus, the neuroendocrine abnormality may provide information that is both complimentary and supplemental to the information currently provided by clinical diagnosis. Thus far there have been no studies which have specifically attempted to examine the possible cognitive and psychophysiologic sequellae of prolonged hypothalamic-pituitary-adrenal disinhibition. In this study we propose to examine psychiatric patients who do and do not show suppression on the dexamethasone suppression test on a battery of assessments selected for their hypothesized and demonstrated sensitivity to alterations in this axis. These include assessment of attention, analgesia, verbal memory, auditory, olfactory, and gustatory sensation thresholds and habituation of galvanic skin response. In addition, for selected subgroups of patients, we plan to conduct a series of 3 studies exploring the relationship of pituitary peptides to cortisol in patient populations defined on these same criteria. Tests proposed include an analysis of circadian regulation, a 2 hour infusion of cortisol, and a 3 hour metyrapone challenge with levels of plasma cortisol, corticotropin and vasopressin assessed.